Association of interleukin 18 (IL18) polymorphisms with specific IgE levels to mite allergens among asthmatic patients

Authors

  • H. D. Shin,

    1. Department of Genetic Epidemiology, SNP Genetics, Inc., MaeHun B/D, Seoul
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  • L. H. Kim,

    1. Department of Genetic Epidemiology, SNP Genetics, Inc., MaeHun B/D, Seoul
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  • B. L. Park,

    1. Department of Genetic Epidemiology, SNP Genetics, Inc., MaeHun B/D, Seoul
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  • Y. H. Choi,

    1. Department of Genetic Epidemiology, SNP Genetics, Inc., MaeHun B/D, Seoul
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  • H.-S. Park,

    1. Asthma Genome Research Group, Soonchunhyang University Hospital, Bucheon, Ajuo University Hospital, Suwon Ulsan University Hospital, Seoul, and Choong-Ang University Hospital, Seoul, South Korea
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  • S.-J. Hong,

    1. Asthma Genome Research Group, Soonchunhyang University Hospital, Bucheon, Ajuo University Hospital, Suwon Ulsan University Hospital, Seoul, and Choong-Ang University Hospital, Seoul, South Korea
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  • B. W. Choi,

    1. Asthma Genome Research Group, Soonchunhyang University Hospital, Bucheon, Ajuo University Hospital, Suwon Ulsan University Hospital, Seoul, and Choong-Ang University Hospital, Seoul, South Korea
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  • J. H. Lee,

    1. Asthma Genome Research Group, Soonchunhyang University Hospital, Bucheon, Ajuo University Hospital, Suwon Ulsan University Hospital, Seoul, and Choong-Ang University Hospital, Seoul, South Korea
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  • C.-S. Park

    1. Asthma Genome Research Group, Soonchunhyang University Hospital, Bucheon, Ajuo University Hospital, Suwon Ulsan University Hospital, Seoul, and Choong-Ang University Hospital, Seoul, South Korea
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Choon-Sik Park
Division of Allergy and Respiratory Medicine
Department of Internal Medicine
Soonchunhyang University Bucheon Hospital
1174, Jung Dong
Wonmi Ku, Bucheon, Gyeonggi Do
Korea 420-021

Abstract

Background:  Allergy is regarded as a multifactorial condition. Its onset and severity are influenced by both genetic and environmental factors. Identification of genetic factors involved in asthma development and related phenotypes is a major task in understanding the genetic background of asthma. The possible involvement of IL18 polymorphisms in asthma was examined in a Korean asthma cohort.

Methods:  Direct sequencing was performed to discover single-nucleotide polymorphisms (SNPs) in the IL18 gene. Single-base extension (SBE) method was employed for genotyping. Genotypic influence of IL18 was analysed using logistic and multiple-regression models.

Results:  Although no polymorphisms in the IL18 gene showed significant association with the risk of asthma development, analyses of the association with specific serum IgE levels to Dermatophagoides farinae (D.f.) and D. pteronyssinus (D.p.) among asthmatic patients revealed significant associations with two completely linked SNPs, i.e. −148G>C and +13925A>C(Ser35Ser) (P = 0.01–0.11 for D.f. and P = 0.005–0.11 for D.p.). Both C allele of −148G>C and C allele of +13925A>C showed gene dose-dependent effects on the levels of specific IgE. The lowest IgE levels in homozygotes of minor alleles (1.13 and 1.22 of D.f.; 1.38 and 1.33 of D.p., respectively), intermediate IgE levels in heterozygotes (1.60 and 1.70 of D.f.; 1.84 and 1.92 of D.p., respectively), and the highest levels in homozygotes for major allele (1.93 and 1.93 of D.f.; 2.24 and 2.24 of D.p., respectively), were found.

Conclusion:  The genetic relevance of IL18 to specific IgE might offer an important step in understanding the genetic background of allergic diseases.

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